Biz

in theatrical slang, means “business.” Good biz means
full houses; but an actor's “biz” is quite another thing, meaning
by-play. Thus, Hamlet trifling with Ophelia's fan, Lord Dundreary's
hop, and so on, are the special “business” of the actor of the part. As
a rule, the “business” is invented by the actor who creates the part,
and is handed down by tradition.